JP2020017452A - Fuel cell system and control method for fuel cell system - Google Patents

Abstract

To suppress freezing of a valve that controls the discharge of water from a gas-liquid separator.SOLUTION: A fuel cell system includes a fuel cell, a gas-liquid separator, a drain passage for discharging water from the gas-liquid separator, a valve for controlling the discharge of water from the gas-liquid separator, and a control unit that controls the operation of the fuel cell and the opening and closing of the valve and determines whether the valve is frozen. The control unit repeatedly determines whether the valve is frozen when receiving a fuel cell stop request during operation of the fuel cell, continues the operation of the fuel cell until it is determined that the valve is not frozen when it has been determined that the valve is frozen, and executes a stop process of the fuel cell, which includes a process of opening the valve when it is determined that there is no freezing of the valve.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell system.

  For the purpose of improving the fuel efficiency of a fuel cell or the like, a configuration is sometimes used in which water is separated from anode off-gas discharged from the fuel cell, and the off-gas after water separation is supplied to the fuel cell for reuse. In such a configuration, a gas-liquid separator that separates and stores moisture from the anode off-gas and a valve that controls discharge of water from the gas-liquid separator may be used. If such a valve freezes in a low temperature environment, the water accumulated in the gas-liquid separator cannot be discharged. Therefore, a method for suppressing freezing of the valve has been proposed. For example, in Patent Document 1, when the operation of the fuel cell is stopped, the flow path connected to the valve is made to have a negative pressure by continuing power generation with the supply of the anode gas being stopped, and the valve is opened in such a state. Thus, a method is disclosed in which the atmosphere is caused to flow toward the valve to move water accumulated near the valve to another position.

JP 2007-35369 A

  However, when the vehicle is used at a temperature below freezing for a short time, the gas-liquid separator and the valve may not be sufficiently heated by the waste heat of the fuel cell and remain frozen. In such a state, according to the method of Patent Document 1, the valve cannot be opened, and the water generated by the power generation accumulates in the gas-liquid separator but is not discharged. Thereafter, when the vehicle stops in a state where the amount of water stored in the vicinity of the gas-liquid separator or the valve is increased, there is a problem that more water is frozen and the valve becomes more difficult to thaw.

  The present disclosure can be realized as the following embodiments.

(1) According to one embodiment of the present disclosure, a fuel cell system is provided. The fuel cell system includes a fuel cell, a gas-liquid separator that separates moisture from an anode off-gas discharged from the fuel cell, and a device that discharges the water separated by the gas-liquid separator from the gas-liquid separator. A drain channel, a valve disposed in the drain channel, for controlling the discharge of the moisture from the gas-liquid separator, and controlling the operation of the fuel cell and the opening and closing of the valve; A control unit for determining the presence or absence of the valve, wherein the control unit repeatedly determines whether or not the valve is frozen when receiving a request to stop the fuel cell during operation of the fuel cell, and freezes the valve. When it is determined that there is no freezing, the operation of the fuel cell is continued until it is determined that there is no freezing of the valve, and when it is determined that there is no freezing of the valve, the fuel cell includes a process of opening the valve. Execute stop processing. According to the fuel cell system of this aspect, the control unit repeatedly determines whether or not the valve is frozen when receiving a request to stop the fuel cell during operation of the fuel cell, and determines that the valve is frozen. Since the operation of the fuel cell is continued until it is determined that the valve is not frozen, the thawing of the valve can be promoted by waste heat accompanying the operation of the fuel cell. Since the fuel cell stop process including the process of opening the fuel cell is performed, the moisture accumulated near the gas-liquid separator and the valve can be discharged through the drain passage, and the freezing of the valve due to the moisture can be suppressed. The phrase “the valve is frozen” means a state in which the opening and closing operation of the valve is hindered by the frozen water. If the opening / closing operation of the valve is hindered, the gas may not be circulated through the valve. The “state in which gas does not flow” means a broad concept including a state in which gas flow is less than a predetermined amount, in addition to a state in which gas flow is not performed at all. Further, "there is no freezing of the valve" means a state in which the gas can be circulated through the valve, in other words, a state in which the gas having a predetermined amount or more can be circulated. It has a broad meaning including the state where frozen water is attached.
(2) In the fuel cell system according to the above aspect, a supply flow path for supplying anode gas to the fuel cell, a circulation flow path that connects the gas-liquid separator and the supply flow path, and the circulation flow path A pump for supplying the anode off-gas after the water has been separated by the gas-liquid separator to the supply flow path, and the stopping process may include driving the pump. According to the fuel cell system of this embodiment, since the stop processing includes driving of the pump, the flow rate of the gas flowing into the fuel cell from the supply flow path, that is, the total flow rate of the anode off-gas and the anode gas after moisture is separated Can be increased as compared with the state where the pump is stopped, and the discharge of water accumulated in the fuel cell can be promoted.
(3) In the fuel cell system according to the above aspect, when the stop processing including the drive of the pump is a first stop processing, the control unit may determine that the valve is frozen, When it is determined that the valve is continuously frozen until a predetermined period elapses after receiving the fuel cell stop request during operation of the fuel cell, the first stop processing is different from the first stop processing. A second stop process, which is the second stop process and does not include the driving of the pump, may be performed. According to the fuel cell system of this aspect, the control unit includes the driving of the pump when determining that the valve is continuously frozen until a predetermined period has elapsed after receiving the stop request. Since the second stop processing, which is a stop processing that is not performed, is performed, it is possible to suppress driving of the pump in a state where the valve is frozen. As the operation of the fuel cell continues, the amount of water stored in the gas-liquid separator may increase. However, according to the fuel cell system of this embodiment, the fuel cell can be stopped without driving the pump in a state where the amount of water stored in the gas-liquid separator is increased. It is possible to prevent the stored water from being sent out toward the fuel cell and entering the fuel cell.
(4) In the fuel cell system according to the above aspect, a supply passage for supplying anode gas to the fuel cell, a circulation passage for communicating the gas-liquid separator with the supply passage, and a gas in the supply passage. And a pressure sensor for detecting pressure, wherein the controller is configured to determine a decrease amount of the gas pressure after transmitting the valve opening instruction with respect to the gas pressure before transmitting the valve opening instruction to the valve. Utilization may be used to determine whether the valve is frozen. According to the fuel cell system of this aspect, the control unit uses the amount of decrease in gas pressure after transmitting the valve opening instruction with respect to the gas pressure before transmitting the valve opening instruction to the valve to determine whether the valve is frozen. Is determined, the freezing of the valve can be accurately determined. If there is no freezing of the valve, the opening of the valve increases in response to the valve opening instruction, and the gas in the gas-liquid separator and the circulation flow path is discharged together with the moisture. The gas pressure in the road decreases. On the other hand, when the valve is frozen, the opening of the valve when the valve opening instruction is transmitted is lower than when the valve is frozen, and the amount of gas discharged through the valve is small. For this reason, the amount of decrease in gas pressure before and after the transmission of the valve opening instruction is different between the case where the valve is frozen and the case where the valve is not frozen. it can.
The present disclosure can be realized in various forms. For example, the present invention can be realized in the form of a vehicle equipped with a fuel cell system, a method of controlling the fuel cell system, a program for executing the method, a storage medium for storing the program, and the like.

1 is a block diagram illustrating a schematic configuration of a fuel cell system according to an embodiment of the present disclosure. 6 is a flowchart illustrating a procedure of a system stop process according to the first embodiment. It is a flowchart which shows the procedure of the exhaust-drain valve freezing determination processing in 1st Embodiment. 9 is a timing chart showing the anode supply pressure, the operating state of the injector, and the content of an operation instruction to the exhaust / drain valve during execution of the exhaust / drain valve freezing determination process. 9 is a timing chart showing execution states of a user operation, a temperature, an exhaust / drain valve freezing determination process, a warm-up process at the time of termination, and a stop process of a fuel cell during a period from system startup to completion of system stop process. It is a flowchart which shows the procedure of the system stop processing in 2nd Embodiment.

A. First embodiment:
A1. System configuration:
FIG. 1 is a block diagram illustrating a schematic configuration of a fuel cell system 10 according to an embodiment of the present disclosure. The fuel cell system 10 outputs electric power generated by an electrochemical reaction of the fuel cell 100 using the anode gas and the cathode gas. In the present embodiment, the fuel cell system 10 is mounted on a vehicle and supplies power to a drive motor of the vehicle. The fuel cell system 10 includes a fuel cell 100, a cathode-side gas supply / discharge mechanism 200, an anode-side gas supply / discharge mechanism 300, and a control unit 600.

  The fuel cell 100 includes a cell stack including a plurality of stacked unit cells 110, and a pair of end plates 111a and 111b. Each single cell 110 includes an anode-side catalyst electrode layer and a cathode-side catalyst electrode layer provided with a solid polymer electrolyte membrane interposed therebetween, and an anode-side gas diffusion layer and a cathode-side gas respectively disposed outside the catalyst electrode layers of both electrodes. A diffusion layer is provided. Hydrogen gas as an anode gas is supplied to the anode-side catalyst electrode layer. Air as a cathode gas is supplied to the cathode-side catalyst layer electrode layer. Each of the catalyst electrode layers of both electrodes includes a catalyst, for example, carbon particles carrying platinum (Pt) and an electrolyte resin. Both gas diffusion layers are formed of a porous material. As the porous body, for example, a carbon porous body such as carbon paper and carbon cloth, and a metal porous body such as a metal mesh and a foamed metal are used. Inside the fuel cell 100, a plurality of manifolds for flowing an anode gas, a cathode gas, an anode off gas, a cathode off gas, and a cooling medium are formed along the stacking direction. In FIG. 1, the anode gas supply manifold 102a and the anode off-gas discharge manifold 102b are shown as representatives. Each of the pair of end plates 111a and 111b is a member having a substantially plate-like appearance, and is disposed at both ends in the stacking direction of the fuel cell 100. The end plate 111a is provided with a through hole in the thickness direction that forms an end of each manifold. Although the cathode-side gas supply / discharge mechanism 200 is illustrated in FIG. 1 as being connected to the fuel cell 100 at the end plate 111b, the cathode-side gas supply / discharge mechanism 200 is connected to the fuel cell 100 at the end plate 111a instead of the end plate 111b. It may be connected.

  The cathode-side gas supply / discharge mechanism 200 supplies a cathode gas to the fuel cell 100 and discharges a cathode off-gas from the fuel cell 100. The cathode-side gas supply / discharge mechanism 200 includes a cathode gas intake flow path 210, a cathode supply flow path 211, a cathode discharge flow path 212, a bypass flow path 213, an air compressor 220, a three-way valve 230, and a back pressure valve. 240.

  The cathode gas intake passage 210 is used to take in air from the atmosphere. One end of the cathode gas intake passage 210 is open to the atmosphere, and the other end is connected to the three-way valve 230. The cathode supply channel 211 guides the compressed air output from the air compressor 220 to the fuel cell 100. One end of the cathode supply channel 211 is connected to the three-way valve 230, and the other end is connected to a cathode supply manifold (not shown) in the fuel cell 100. The cathode discharge channel 212 guides the anode off-gas discharged from the fuel cell 100 to the outside. One end of the cathode discharge passage 212 is connected to a cathode offgas discharge manifold (not shown) in the fuel cell 100, and the other end is connected to a bypass passage 213. The bypass passage 213 is used for discharging a part of the compressed air output from the air compressor 220 without passing through the fuel cell 100. One end of the bypass passage 213 is connected to the three-way valve 230, and the other end is open to the atmosphere. The bypass flow path 213 is connected to a drain flow path 312 described below in addition to the cathode discharge flow path 212 described above. The cathode off-gas discharged from the fuel cell 100 through the cathode discharge flow path 212, and the moisture and the anode off-gas discharged from the drain flow path 312 are generated in the atmosphere by air flowing from the air compressor 220 into the bypass flow path 213. Is discharged to Here, the “water discharged from the drain passage 312” includes the water separated by the gas-liquid separator 360. The moisture includes liquid water, water vapor, and atomized water.

  The air compressor 220 is disposed in the cathode gas intake channel 210. The air compressor 220 sucks in air from which foreign matter such as dust has been removed by an air cleaner (not shown), and compresses and outputs the air. The three-way valve 230 connects the cathode gas intake channel 210, the cathode supply channel 211, and the bypass channel 213. The three-way valve 230 adjusts the flow rate of the compressed air output from the air compressor 220 sent to the cathode supply flow path 211 and the flow rate sent to the bypass flow path 213. The back pressure valve 240 is provided in the cathode discharge channel 212, and adjusts the gas pressure on the cathode off gas discharge side in the fuel cell 100.

  The anode-side gas supply / discharge mechanism 300 supplies an anode gas to the fuel cell 100 and discharges an anode off-gas from the fuel cell 100. The anode-side gas supply / discharge mechanism 300 includes an anode gas supply passage 310, a circulation passage 311, a drain passage 312, a hydrogen gas tank 320, a shutoff valve 330, a pressure regulating valve 340, an injector 350, a gas-liquid It includes a separator 360, a pump 370, an exhaust / drain valve 380, and a pressure sensor 390.

  The anode gas supply channel 310 guides the anode gas to the fuel cell 100. One end of the anode gas supply channel 310 is connected to the hydrogen gas tank 320, and the other end is connected to the anode gas supply manifold 102 a in the fuel cell 100. The circulation channel 311 connects the gas-liquid separator 360 and the anode gas supply channel 310. The connection point between the circulation channel 311 and the anode gas supply channel 310 is located between the injector 350 and the fuel cell 100. The drain passage 312 is used for discharging the water separated by the gas-liquid separator 360 from the gas-liquid separator 360. One end of the drain passage 312 is connected to the gas-liquid separator 360, and the other end is connected to the bypass passage 213.

  The hydrogen gas tank 320 stores high-pressure hydrogen gas as an anode gas. The shutoff valve 330 is arranged near the hydrogen gas tank 320 in the anode gas supply channel 310, and switches between execution and stop of the supply of the hydrogen gas from the hydrogen gas tank 320. The pressure regulating valve 340 is disposed downstream of the shutoff valve 330 and upstream of the injector 350 in the anode gas supply channel 310. The pressure regulating valve 340 adjusts the secondary pressure on the downstream side to a preset pressure by reducing the primary pressure on the upstream side thereof. The injector 350 is disposed downstream of the pressure regulating valve 340 in the anode gas supply channel 310. The injector 350 injects anode gas to the fuel cell 100. At this time, by adjusting the injection cycle and the injection duty of the anode gas in the injector 350, the supply amount of the anode gas to the fuel cell 100 and the gas pressure of the anode gas supply channel 310 can be adjusted. Note that the injection duty means the ratio of the time during which hydrogen gas is injected per one injection cycle.

  The anode gas is supplied to each single cell 110 through the anode gas supply manifold 102a. Then, part of the anode gas supplied in each single cell 110 is consumed, and unused anode gas is discharged to the gas-liquid separator 360 via the anode off-gas discharge manifold 102b as anode off-gas. The gas-liquid separator 360 separates moisture from the anode off-gas discharged from the fuel cell 100. The anode off-gas includes, in addition to the residual hydrogen gas not used in the electrochemical reaction in each single cell 110, nitrogen gas that has permeated from the cathode side to the anode side through the electrolyte membrane. Further, the anode off-gas contains water permeated from the cathode side to the anode side via the electrolyte membrane in each single cell 110. The gas-liquid separator 360 separates moisture contained in the anode off-gas from the anode off-gas. In the present embodiment, the gas-liquid separator 360 includes a recess provided on the end plate 111a and a cover member that covers the recess. The concave portion provided in the end plate 111a is open on the outer surface of the end plate 111a, and has a shape in which the thickness direction of the end plate 111a is the depth direction. A communication hole with the anode off-gas discharge manifold 102b is provided in such a concave portion. A recess similar to the recess provided on the end plate 111a is formed inside the cover member described above. A space for gas-liquid separation and water retention (hereinafter, referred to as a “separation space”) is formed by the two concave portions facing each other and communicating with each other. When the anode off-gas flows into the separation space and collides with the inner wall surface, moisture in the anode off-gas condenses and is guided below the separation space. A communication hole communicating with the drain passage 312 is provided at the lowermost part of the sharing space. When the exhaust / drain valve 380 is closed, water accumulates in the separation space. On the other hand, when the exhaust / drain valve 380 is in the open state, the water collected in the separation space is discharged. A communication hole with the circulation channel 311 is provided above the separation space. The anode off-gas from which the water has been separated flows into the circulation channel 311 from the communication hole. Since the gas-liquid separator 360 has a part of the end plate 111a as a constituent element, waste heat generated during operation of the fuel cell 100 is easily transmitted to the gas-liquid separator 360.

  The pump 370 is disposed in the circulation channel 311, and supplies the anode off-gas from which moisture has been separated by the gas-liquid separator 360 to the anode gas supply channel 310. The anode off-gas from which the water has been separated contains the remaining anode gas not used in each single cell 110 as described above. Therefore, in the fuel cell system 10 of the present embodiment, the anode off-gas is returned to the anode gas supply channel 310 and supplied again to the fuel cell 100, thereby improving fuel efficiency.

  The exhaust / drain valve 380 is disposed in the drain passage 312 and controls the discharge of moisture from the gas-liquid separator 360. In the present embodiment, the exhaust / drain valve 380 is disposed in contact with the gas-liquid separator 360. In the present embodiment, the exhaust / drain valve 380 is constituted by an on-off valve. Therefore, one of the two states, the open state and the closed state, can be selectively set. When the exhaust / drain valve 380 is in the open state, the above-described separation space communicates with the drain channel 312, and water accumulated in the gas-liquid separator 360 is discharged to the drain channel 312 via the exhaust / drain valve 380. You. On the other hand, when the exhaust / drain valve 380 is in the closed state, the space for separation and the drain passage 312 do not communicate with each other, and therefore, the water accumulated in the gas-liquid separator 360 is not discharged. It should be noted that the exhaust / drain valve 380 may be configured by any other type of valve that can be adjusted to a plurality of openings, instead of the on-off valve.

  Pressure sensor 390 detects gas pressure in anode gas supply channel 310 (hereinafter, referred to as “anode supply pressure”). In the present embodiment, the pressure sensor 390 is arranged at a position closer to the hydrogen gas tank 320 in the anode gas supply channel 310 than to a connection point with the circulation channel 311. As described above, the hydrogen gas injected from the injector 350 and the anode off-gas sent from the pump 370 via the circulation passage 311 are supplied to the anode gas supply passage 310. Therefore, pressure sensor 390 detects the total pressure of these gases as the anode supply pressure.

  The control unit 600 controls the operation of the fuel cell 100 and the opening / closing of the exhaust / drain valve 380, and determines whether or not the exhaust / drain valve 380 is frozen. In the present embodiment, the control unit 600 is configured by a computer having a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The CPU executes a control program stored in the ROM in advance to control the operation of the fuel cell 100, control the opening and closing of the exhaust / drain valve 380, determine whether the exhaust / drain valve 380 is frozen, and the like. Functions as a unit. In the present embodiment, each of the valves 230, 240, 330, 340, and 380 is an electromagnetic valve, and is electrically connected to the control unit 600. The control unit 600 controls the opening degree of each of the valves 230, 240, 330, 340, and 380 or controls the switching operation of opening and closing. Further, control unit 600 is electrically connected to air compressor 220, injector 350, and pump 370, respectively, and controls operations of air compressor 220, injector 350, and pump 370.

  The controller 600 controls the operation of the fuel cell 100 and the opening / closing of the exhaust / drain valve 380, and determines whether or not the exhaust / drain valve 380 is frozen. Execute the control of. For example, the control unit 600 receives a drive request and a stop request transmitted from a vehicle control device (not shown) mounted on the vehicle, and executes the operation of the fuel cell 100 or a system stop process described below in response to these requests. . When the operation of the fuel cell 100 is performed, the control unit 600 uses the information of the accelerator opening and the vehicle speed received from the vehicle control device and the information indicating the operation state of the auxiliary devices, etc. The operating point of the fuel cell 100 including the voltage value is determined, and the flow rates of the hydrogen gas and the air supplied to the fuel cell 100 to realize the operating point are determined. Further, the control unit 600 controls the valves 330, 340, 230, 240, the injector 350, the pump 370, and the air compressor 220 so as to realize the determined flow rates of the hydrogen gas and the air. In addition, during operation of the fuel cell 100, the control unit 600 periodically controls the exhaust / drain valve 380 to perform an opening operation, thereby controlling the water accumulated in the gas-liquid separator 360 to be discharged. Further, control section 600 performs feedback control for controlling the injection amount and injection duty of injector 350 based on the pressure value detected by pressure sensor 390.

  Although omitted in FIG. 1, the fuel cell system 10 includes a cooling medium circulation mechanism and a power supply circuit in addition to the above-described fuel cell 100, the cathode-side gas supply / discharge mechanism 200, and the anode-side gas supply / discharge mechanism 300. I have. The cooling medium circulation mechanism adjusts the temperature of the fuel cell 100 by circulating the cooling medium in a circulation flow path including a cooling medium supply manifold and a cooling medium discharge manifold provided in the fuel cell 100. The cooling medium circulation mechanism includes a radiator, a pump for circulating the cooling medium, and the like, in addition to the above-described cooling medium circulation flow path. The power supply circuit supplies power from at least one of the fuel cell 100 and a secondary battery (not shown) to a drive motor mounted on the vehicle and various auxiliary machines. The power supply circuit includes a DC-DC converter and an inverter.

  The above-described anode gas supply channel 310 corresponds to a lower concept of the supply channel in the means for solving the problem. Further, the exhaust / drain valve 380 corresponds to a subordinate concept of the valve in the means for solving the problem.

A2. Control of the fuel cell system 10:
As described above, the control unit 600 controls the fuel cell system 10. The control of the fuel cell system 10 includes a system stop process. As will be described later, freezing of the exhaust / drain valve 380 is suppressed by executing the system stop processing.

  FIG. 2 is a flowchart illustrating a procedure of a system stop process according to the first embodiment. When the vehicle stops and the user performs a stop operation, for example, presses a vehicle stop button, the vehicle control device transmits a request to stop the fuel cell 100 to the control unit 600. When such a stop request is received by control unit 600, a system stop process is started. When the user performs a stop operation, the vehicle is stopped, and the operation of the fuel cell 100 for supplying power to the auxiliary devices (hereinafter, referred to as “idling operation”) is being performed.

  The control unit 600 executes a process of determining whether or not the exhaust / drain valve is frozen (hereinafter, referred to as “exhaust / drain valve freeze determination process”) (step S105). In the present embodiment, “there is freezing” means a state in which the open / close operation of the exhaust / drain valve 380 is hindered by the frozen water. If the opening / closing operation of the exhaust / drain valve 380 is hindered, the gas may not be circulated through the exhaust / drain valve 380 in some cases. The above-mentioned "state in which gas does not flow" means a broad concept including a state in which gas flow is less than a predetermined amount, in addition to a state in which gas flow is not performed at all. On the other hand, "no freezing" refers to a state in which gas can flow through the exhaust / drain valve 380, in other words, a state in which gas of a predetermined amount or more can be passed. It has a broad meaning, including the state where frozen water is attached to a part of the surface. The predetermined amount of the gas may be, for example, 100 ml (milliliter) as a total flow rate during execution of the exhaust / drain valve freezing determination process. The amount is not limited to 100 ml and may be any amount. For example, it may be any value between 0 ml and 200 ml. More preferably, it may be any value between 0 ml and 100 ml.

  FIG. 3 is a flowchart illustrating a procedure of an exhaust / drain valve freeze determination process according to the first embodiment. Control unit 600 specifies the anode supply pressure by receiving the detection value transmitted from pressure sensor 390 (step S205). After instructing the exhaust / drain valve 380 to perform an opening operation, the controller 600 specifies the anode supply pressure again (step S210). As described above, the control unit 600 periodically instructs the exhaust / drain valve 380 to perform the opening operation. After the opening operation instruction after step S205 is executed, step S210 is executed, and the anode supply is performed. The pressure is specified again.

  The control unit 600 determines whether or not the anode supply pressure specified in step S210 has decreased from a pressure specified last time (hereinafter, referred to as a “previous specified value”) by a predetermined threshold or more (step S215). When it is determined that the anode supply pressure has not decreased from the previous specific value by a predetermined threshold or more (step S215: NO), the control unit 600 determines that the exhaust / drain valve 380 is frozen (step S220).

  On the other hand, when it is determined that the anode supply pressure has decreased by the predetermined threshold value or more from the previous specific value (step S215: YES), the control unit 600 determines that the anode supply pressure has decreased by the predetermined value or more from the previous specific value. (Determination result) is determined to be the fifth determination (determination result) after the start of the exhaust / drain valve freezing determination process (step S225). If it is determined that it is not the fifth determination (step S225: NO), the process returns to step S210. On the other hand, when it is determined that the determination is the fifth determination (step S225: YES), the control unit 600 determines that the exhaust / drain valve 380 is not frozen (step S230). If it is determined in step S215 that the anode supply pressure has not decreased by a predetermined value or more from the previous specified value before the fifth determination, it is determined that there is freezing as described above, and the exhaust / drain valve freeze determination is performed. The process ends. Therefore, the case where it is determined to be the fifth determination in step S225 means the case where it is determined that "the anode supply pressure has decreased by a predetermined value or more from the previous specified value" five times in a row. In this case, it is determined that the exhaust / drain valve 380 is not frozen.

  FIG. 4 is a timing chart showing the anode supply pressure, the operation state of the injector 350, and the contents of an operation instruction to the exhaust / drain valve 380 during execution of the exhaust / drain valve freezing determination process. 4, the upper part shows the anode supply pressure, the middle part shows the operating state of the injector 350, and the lower part shows the operating state of the exhaust / drain valve 380. In FIG. 4, the horizontal axis indicates time. The anode supply pressure when the exhaust / drain valve 380 is frozen is indicated by a thick solid line, and the anode supply pressure when the exhaust / drain valve 380 is not frozen is indicated by a broken line. The ON state of the injector 350 indicates a state in which the injector 350 is injecting hydrogen gas, and the OFF state of the injector 350 indicates a state in which hydrogen gas is not being injected. “Opening” of the exhaust / drain valve 380 means that the control unit 600 instructs the exhaust / drain valve 380 to perform an opening operation. Further, “close” of the exhaust / drain valve 380 means that the control unit 600 instructs the exhaust / drain valve 380 to perform a closing operation.

  The anode supply pressure increases during the period from time T1 to time T2 when the injector 350 injects hydrogen gas. When the injection of the hydrogen gas by the injector 350 is stopped at the time T2, the anode supply pressure starts to decrease with the consumption of the hydrogen gas in the fuel cell 100, and then the anode supply pressure until the time T5 when the injection of the hydrogen gas by the injector 350 is started. The supply pressure continues to drop. When there is no freezing of the exhaust / drain valve 380, when an opening operation instruction is received at time T4 before time T5, the exhaust / drain valve 380 opens. Therefore, the water accumulated in the gas-liquid separator 360 is discharged through the drain passage 312, and the gas in the circulation passage 311 is discharged to the drain passage 312. Therefore, the amount of decrease in the anode supply pressure per unit time sharply increases as shown by the broken line in FIG. 4, and the anode supply pressure rapidly decreases.

  On the other hand, when the exhaust / drain valve 380 is frozen, the exhaust / drain valve 380 is not opened in the closed state even when the opening operation instruction is received at the time T4. Therefore, neither the water accumulated in the gas-liquid separator 360 nor the gas in the circulation channel 311 is discharged, and the amount of decrease in the anode supply pressure per unit time changes before the opening operation instruction is received. do not do. Therefore, the amount of decrease in the anode supply pressure at time T5 after the transmission of the opening operation instruction with respect to the anode supply pressure at time T3 before the time T4 when the opening operation instruction is transmitted when the exhaust / drain valve 380 is frozen. ΔP1 (hereinafter simply referred to as “pressure drop amount”) is smaller than the pressure drop amount ΔP2 when there is no freezing. Therefore, by setting the predetermined threshold value of the above-described step S215 to a value larger than the pressure reduction amount ΔP1 and smaller than the pressure reduction amount ΔP2, freezing is performed when the reduction amount of the anode supply pressure falls below the predetermined threshold value. It is determined that there is no freezing, and it is determined that there is freezing if it does not drop below a predetermined threshold. In the present embodiment, the time T3 is set as the time T2, that is, the timing after a lapse of a predetermined time from the time when the injector 350 changes from on to off. The time T5 is set as a time T4, that is, a timing after a lapse of a predetermined time from the time when the instruction to open the exhaust / drain valve 380 is transmitted. The difference in the amount of pressure drop depending on whether the exhaust / drain valve 380 is frozen or not may occur not only at the anode supply pressure at the time T3 and the time T5 but also at the anode supply pressure at any time before and after the transmission of the opening operation instruction. Therefore, the setting method of the time T3 and the time T5 is not limited to the above method, and the time before and after the transmission of the opening operation instruction may be set by any method that can be set. As shown in FIG. 2, after the above step S220 or S230 is executed, step S110 shown in FIG. 2 is executed.

  The control unit 600 determines whether or not the exhaust / drain valve 380 is frozen based on the result of the exhaust / drain valve freezing determination process (Step S110). When it is determined that the exhaust / drain valve 380 is frozen (step S110: YES), the control unit 600 continues operating the fuel cell 100 (step S125). As described above, when the system stop processing is executed, the vehicle is stopped and the idling operation is being executed. In step S125, the idling operation is continuously performed. After step S125, the process returns to step S105. In FIG. 2, step S125 is shown as one step for convenience, but step S125 may be omitted. Even in such a configuration, the idling operation is continuously performed. As described above, since a part of the gas-liquid separator 360 is constituted by the end plate 111a, the waste heat of the fuel cell 100 is continuously supplied to the gas-liquid separator 360 by performing the idling operation continuously. , And continuously from the gas-liquid separator 360 to the exhaust / drain valve 380. For this reason, the thawing of the exhaust / drain valve 380 is promoted, and it is determined that the exhaust / drain valve 380 is not frozen in step S110 while the idling operation is continued.

  When it is determined that the exhaust / drain valve 380 is not frozen (step S110: NO), the control unit 600 executes the termination warm-up (step S115). The end-time warm-up means a rapid warm-up executed as one step of the system stop process, and the same process as the start-up warm-up is executed. Specifically, the fuel cell 100 is operated at an operating point where the power generation efficiency is lower than in the normal operation. For example, a process of reducing the power generation efficiency by extremely reducing the amount of supplied air as compared with a normal idling operation may be executed. By performing the warm-up at the time of termination, the waste heat of the fuel cell 100 increases. For this reason, the evaporation of the water in the fuel cell 100 can be promoted, and the discharge of the water in the fuel cell 100 can be promoted in the stop processing described later.

  After execution of step S115, control unit 600 executes a stop process of fuel cell 100 (step S120). In the present embodiment, in the stop processing of the fuel cell 100, in addition to the stop of the operation of the injector 350 and the air compressor 220 due to the stop of the power supply to the auxiliary equipment, the driving of the pump 370 and the opening operation of the exhaust / drain valve 380 are performed. Is included. By driving the pump 370, the amount of gas flowing into the anode side of the fuel cell 100 can be increased, and more water in the fuel cell 100 can be discharged. In addition, the moisture accumulated in the gas-liquid separator 360 due to the opening operation of the exhaust / drain valve 380 and the moisture in the fuel cell 100 vaporized by the warm air at the end, that is, water vapor, are discharged. When step S120 is performed, the exhaust drainage valve 380 is not frozen by the execution of step S115. Therefore, when an instruction to open the exhaust drainage valve 380 is transmitted to the exhaust drainage valve 380, the exhaust drainage valve 380 is stopped. The opening operation is actually performed. Therefore, the above-described discharge of moisture and water vapor is performed. After execution of step S120, the system stop processing ends.

  FIG. 5 is a timing chart showing the state of execution of the user operation, the temperature, the exhaust / drain valve freezing determination process, the warm-up process at the time of termination, and the stop process of the fuel cell 100 during the period from the start of the system to the completion of the system stop process. . In FIG. 5, the top row indicates the user operation, the second row from the top indicates the temperature, the third row from the top indicates the processing result of the exhaust / drain valve freezing determination processing, and the fourth row from the top indicates the end-time warm air. The bottom row shows the process of stopping the fuel cell 100. In FIG. 5, the horizontal axis indicates time. In “temperature”, a thick solid line indicates the temperature of the cooling medium circulated by the cooling medium circulating mechanism (hereinafter, referred to as “FC water temperature”), and a thin dashed line indicates the temperature of the exhaust / drain valve 380 (hereinafter, “valve”). Temperature).

  When the user turns on the start switch (ST) of the vehicle at time T11, the fuel cell 100 starts, and the FC water temperature and the valve temperature rise. Thereafter, at time T12, the user presses down (IG_OFF) the vehicle stop switch. That is, the vehicle is driving during the period from time T11 to T12. In the example of FIG. 5, during the period from time T11 to time T12, the exhaust / drain valve 380 is continuously frozen. Such a situation may occur, for example, when the vehicle is driven for a short time in a low-temperature environment of 0 ° C. or less. The FC water temperature continues to increase after time T12, and starts decreasing at time T13. The cooling medium heated by the waste heat during the normal operation of the fuel cell 100 continues to circulate even after the vehicle stops, so that the water temperature continues to rise. However, when the idling operation is performed and the amount of waste heat decreases, the FC water temperature starts to decrease. It will be. The valve temperature increases from time T11 and continues to increase even after time T13. This is because the waste heat of the fuel cell 100 is transmitted to the exhaust / drain valve 380 by the continuous execution of the idling operation after the time T13 (step S125). Thereafter, when it is determined at time T14 that the exhaust / drain valve 380 is not frozen, warm-up at the end is performed (step S115), and the FC water temperature rises sharply. At the time T15, when the termination warm-up ends, the FC temperature and the valve temperature decrease. At this time, since the exhaust / drain valve 380 is not frozen, the exhaust / drain valve 380 can perform an opening operation when the stop processing is executed, and the water accumulated in the exhaust / drain valve 380 is discharged to the outside.

  According to the fuel cell system 10 of the first embodiment described above, the control unit 600 repeatedly determines whether or not the exhaust / drain valve 380 is frozen when receiving a request to stop the fuel cell 100 during operation of the fuel cell 100. When it is determined that the exhaust / drain valve 380 is frozen, the idling operation is continued until it is determined that the exhaust / drain valve 380 is not frozen. Thawing can be promoted. When it is determined that the exhaust / drain valve 380 is not frozen, the fuel cell 100 is stopped, including the process of opening the exhaust / drain valve 380, so that the fuel / drain valve 380 accumulates near the gas-liquid separator 360 and the exhaust / drain valve 380. The drained water can be discharged through the drain passage 312, and the freezing of the exhaust / drain valve 380 due to such water can be suppressed.

  Further, since the stop process includes the driving of the pump 370, the flow rate of the gas supplied from the anode gas supply channel 310 to the fuel cell 100, that is, the total flow rate of the anode off gas and the hydrogen gas after the water has been separated is pumped. 370 can be increased as compared with the stopped state, and the discharge of water accumulated in the fuel cell 100 can be promoted.

  In addition, the control unit 600 uses the amount of decrease in the anode supply pressure after the transmission of the valve opening instruction with respect to the anode supply pressure before transmitting the valve opening instruction to the exhaust and drainage valve 380 to freeze the exhaust and drainage valve 380. Since the presence or absence is determined, the freezing of the exhaust / drain valve 380 can be accurately determined. When the exhaust / drain valve 380 is not frozen, the opening of the exhaust / drain valve 380 increases in accordance with the valve opening instruction, and the gas in the gas-liquid separator 360 and the circulation channel 311 is discharged together with the water. The gas pressure in the anode gas supply channel 310 communicating with the circulation channel 311 decreases. On the other hand, when the exhaust / drain valve 380 is frozen, the degree of opening of the exhaust / drain valve 380 when the valve opening instruction is transmitted is lower than when the exhaust / drain valve 380 is frozen. The amount of gas exhausted through is small. For this reason, the amount of decrease in the anode supply pressure before and after the transmission of the valve opening instruction differs depending on whether the exhaust / drain valve 380 is frozen or not. Therefore, according to the fuel cell system 10, the freezing of the exhaust / drain valve 380 can be accurately determined.

B. Second embodiment:
Since the system configuration of the fuel cell system 10 of the second embodiment is the same as that of the fuel cell system 10 of the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof will be omitted.

  FIG. 6 is a flowchart illustrating a procedure of a system stop process according to the second embodiment. The system stop processing of the second embodiment is different from the system stop processing of the first embodiment in that steps S123 and S130 are additionally performed. Other procedures in the system stop processing according to the second embodiment are the same as those in the system stop processing according to the first embodiment. Therefore, the same steps are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In the present embodiment, the stop processing of the fuel cell 100 performed in step S120 is referred to as “first stop processing”. This is to distinguish it from a second stop process described later. In the first stop processing, the pump 370 is driven as described above.

  When it is determined in step S110 that the exhaust / drain valve 380 is frozen (step S110: YES), the control unit 600 determines whether or not a predetermined time has elapsed after receiving the stop request (step S123). In the present embodiment, the predetermined time is set to 5 minutes. The predetermined time is not limited to 5 minutes and may be set to an arbitrary time. When it is determined that the predetermined time has not elapsed from the reception of the stop request (step S123: NO), the above-described step S125 is executed, and the idling operation is continued. On the other hand, when it is determined that the predetermined time has elapsed from the reception of the stop request (step S123: YES), control unit 600 executes a second stop process (step S130), and the system stop process ends.

  The second stop processing differs from the first stop processing in that the pump 370 is not driven. Therefore, the second stop processing includes the stop of the operation of the injector 350 and the air compressor 220 due to the stop of the power supply to the auxiliary equipment, and the opening operation of the exhaust / drain valve 380. However, when the second stop processing is executed, the exhaust / drain valve 380 cannot be opened even if an instruction for the opening operation is transmitted because the exhaust / drain valve 380 is frozen.

  The fuel cell system 10 according to the second embodiment described above has the same effects as the fuel cell system 10 according to the first embodiment. In addition, when the control unit 600 determines that the exhaust / drain valve 380 is continuously frozen until a predetermined period has elapsed after receiving the stop request, the control unit 600 performs a stop process that does not include driving of the pump 370. Since the two-stop process is performed, it is possible to suppress driving of the pump 370 when the exhaust / drain valve 380 is frozen. As the idling operation continues, the amount of water stored in the gas-liquid separator 360 increases. However, in the fuel cell system 10 of the second embodiment, since the fuel cell 100 can be stopped without driving the pump 370 in such a state, the water stored in the gas-liquid separator 360 due to the driving of the pump 370 causes the fuel cell 100 to stop. It can be suppressed that the fuel cell 100 is sent out toward the fuel cell 100 and enters the fuel cell 100. For this reason, the occurrence of flooding can be suppressed, and a decrease in the power generation efficiency of the fuel cell 100 can be suppressed.

C. Other embodiments:
C1. Other Embodiment 1:
In each embodiment, the stop processing and the first stop processing include the driving of the pump 370, but may not include the driving of the pump 370. In such a configuration, the same effect as in each embodiment can be obtained. In general, the pressure of the circulation channel 311 is controlled to be equal to or higher than the atmospheric pressure in order to prevent gas from flowing from the atmosphere. Therefore, even in a configuration in which the pump 370 is not driven, the water accumulated in the gas-liquid separator 360 can be discharged by opening the exhaust / drain valve 380. Further, according to the above configuration, since the driving of the pump 370 is not included, it is possible to prevent the water accumulated in the gas-liquid separator 360 from being sent out into the fuel cell 100 by the pump 370, in other words, being pumped. In the second stop process of the second embodiment, transmission of an instruction to open the exhaust / drain valve 380 may be omitted. When the second stop process is performed, the exhaust / drain valve 380 is frozen. Therefore, with the above-described configuration, it is not necessary to transmit a useless opening operation instruction, and power consumption of the control unit 600 can be suppressed.

C2. Other Embodiment 2:
In each embodiment, in the exhaust water drain valve freezing determination process, when it is determined that “anode supply pressure has decreased from the previous specified value by a predetermined value or more” five consecutive times, it is determined that the exhaust water drain valve 380 is not frozen. However, if it is determined that the “anode supply pressure has decreased by a predetermined value or more from the previous specified value” continuously for an arbitrary number such as once or six times, not limited to five times, the exhaust / drain valve 380 May not be frozen.

  Further, in each embodiment, the freezing of the exhaust / drain valve 380 is determined by whether or not the amount of decrease in the anode supply pressure after the transmission of the valve opening instruction with respect to the anode supply pressure before the transmission of the valve opening instruction has decreased by a predetermined threshold or more. However, the present disclosure is not limited to this. For example, the value of the anode supply pressure when the opening operation is instructed to the exhaust / drain valve 380 is determined in advance by an experiment, whether or not the exhaust / drain valve 380 is frozen. In addition, predetermined pressure value ranges including the obtained values are set as a pressure value range when there is freezing and a pressure value range when there is no freezing. Then, the presence or absence of freezing of the exhaust / drain valve 380 may be determined based on whether or not the anode supply pressure value specified in step S210 is included in the pressure value range in any case. Further, for example, in a configuration in which the vehicle can obtain the outside air temperature, the control unit 600 obtains the obtained outside air temperature, and when the obtained outside air temperature is equal to or lower than a predetermined temperature, the freezing of the exhaust / drain valve 380 is prevented. If the temperature is higher than the predetermined temperature, it may be determined that the exhaust / drain valve 380 is not frozen. The predetermined temperature may be, for example, 0 ° C. Further, for example, a temperature sensor is arranged near the exhaust / drain valve 380, and when the detected temperature of the temperature sensor is equal to or lower than a predetermined temperature, it is specified that the exhaust / drain valve 380 is frozen, and when it is higher than the predetermined temperature, It may be determined that the exhaust / drain valve 380 is not frozen. The predetermined temperature in such a configuration may be, for example, 0 ° C. Also, for example, a gas flow sensor is arranged in the drain flow path 312 on the downstream side of the exhaust / drain valve 380 and near the exhaust / drain valve 380, and the gas flow rate detected by the gas flow sensor is equal to or less than a predetermined flow rate. In this case, it may be specified that the exhaust / drain valve 380 is frozen, and if the flow rate is larger than the predetermined flow rate, it may be determined that the exhaust / drain valve 380 is not frozen. The predetermined flow rate in such a configuration may be, for example, 100 ml. Further, for example, when the exhaust / drain valve 380 is a solenoid valve, a current value when a voltage is applied to the exhaust / drain valve 380 is measured, and the presence / absence of freezing of the exhaust / drain valve 380 is determined based on the current value. Is also good. When the exhaust / drain valve 380 is frozen, the current flowing when a voltage is applied to the exhaust / drain valve 380 is larger than when it is not frozen. Therefore, when the measured current value is equal to or larger than the threshold current, it may be determined that the exhaust / drain valve 380 is frozen.

C3. Other Embodiment 3:
In each embodiment, the control unit 600 is configured as a computer mounted on a vehicle, but the present disclosure is not limited to this. For example, the vehicle may be configured to communicate with a management server (not shown), and the management server may function as the control unit 600. In such a configuration, the vehicle receives the instruction from the management server, and returns a communication device for returning an execution result of a process corresponding to the instruction to the management server, and each valve 230 according to the instruction received from the management server. , 240, 330, 340, and 380, the air compressor 220, the injector 350, and a controller that controls the pump 370. Communication between the vehicle and the management server in such a configuration may be realized, for example, as communication using ITS (Intelligent Transport System). Further, for example, a microcomputer provided in another vehicle different from the vehicle may function as the control unit 600 of each embodiment. In such a configuration, the vehicle and another vehicle may perform so-called vehicle-to-vehicle communication to transmit and receive an instruction for each operation and to transmit and receive an execution result of a process according to the instruction.

C4. Other Embodiment 4:
In each embodiment, the fuel cell system 10 is mounted on a vehicle and used as a system for supplying electric power to a drive motor, but the present disclosure is not limited to this. For example, in place of a vehicle, it may be used by being mounted on any other moving object requiring a driving power supply such as a ship or an airplane. Further, as a stationary power supply, for example, it may be installed indoors or outdoors in an office or home and used. Further, each single cell 110 included in the fuel cell 100 is a single cell for a polymer electrolyte fuel cell, but a phosphoric acid fuel cell, a molten carbonate fuel cell, a solid oxide fuel cell, etc. It may be configured as a single cell for various fuel cells.

C5. Other Embodiment 5:
The configuration of the fuel cell system 10 in each embodiment is merely an example, and can be variously changed. For example, a configuration may be adopted in which the off-gas is independently discharged without connecting the drain flow path 312 and the bypass flow path 213. Further, the gas-liquid separator 360 has the end plate 111a as a part of a component, but may be configured as a device independent of the end plate 111a. In such a configuration, the exhaust / drain valve 380 may be configured not to be in contact with the gas-liquid separator 360, and may be connected to the gas-liquid separator 360 by a pipe. Also in such a configuration, waste heat accompanying idling operation of the fuel cell 100 generates a pipe connecting the fuel cell 100 and the gas-liquid separator 360 and a pipe connecting the gas-liquid separator 360 and the exhaust / drain valve 380. , And can promote thawing of the exhaust / drain valve 380. The position of the pressure sensor 390 is closer to the hydrogen gas tank 320 in the anode gas supply flow path 310 than to the connection point with the circulation flow path 311, but is closer to the fuel cell 100 than this connection point. It may be.

C6. Other Embodiment 6:
In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, at least a part of the function of the control unit 600 may be realized by an integrated circuit, a discrete circuit, or a module in which those circuits are combined. Further, when part or all of the functions of the present disclosure are realized by software, the software (computer program) can be provided in a form stored in a computer-readable recording medium. The “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but may be fixed to an internal storage device in the computer such as various RAMs or ROMs or a computer such as a hard disk. It also includes the external storage device that is used. That is, the “computer-readable recording medium” has a broad meaning including any recording medium that can fix data packets, not temporarily.

  The present disclosure is not limited to the above-described embodiments, and can be implemented with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary of the invention may be used to solve some or all of the above-described problems, or to provide one of the above-described effects. In order to achieve a part or all, replacement or combination can be appropriately performed. If the technical features are not described as essential in this specification, they can be deleted as appropriate.

  Reference Signs List 10: fuel cell system, 100: fuel cell, 102a: anode gas supply manifold, 102b: anode off gas discharge manifold, 110: single cell, 111a: end plate, 111b: end plate, 200: cathode side gas supply / discharge mechanism, 210 ... Cathode gas intake passage, 211 ... Cathode supply passage, 212 ... Cathode discharge passage, 213 ... Bypass passage, 220 ... Air compressor, 230 ... Three-way valve, 240 ... Back pressure valve, 300 ... Anode side gas supply / discharge Mechanism: 310: anode gas supply channel, 311: circulation channel, 312: drain channel, 320: hydrogen gas tank, 330: shut-off valve, 340: pressure regulating valve, 350: injector, 360: gas-liquid separator, 370 ... Pump, 380: exhaust / drain valve, 390: pressure sensor, 600: control unit, Δ 1 ... pressure reduction amount, ΔP2 ... pressure reduction amount, T1~T5, T11~T15 ... time

Claims (5)

A fuel cell system,
A fuel cell,
A gas-liquid separator for separating water from the anode off-gas discharged from the fuel cell,
A drain passage for discharging the water separated by the gas-liquid separator from the gas-liquid separator,
A valve disposed in the drain passage to control discharge of the moisture from the gas-liquid separator;
A control unit that controls the operation of the fuel cell and the opening and closing of the valve, and determines whether the valve is frozen.
With
The control unit, when receiving a request to stop the fuel cell during operation of the fuel cell,
Repeatedly determining the presence or absence of freezing of the valve,
When determining that there is freezing of the valve, continue operating the fuel cell until determining that there is no freezing of the valve,
When it is determined that there is no freezing of the valve, executing a stop process of the fuel cell including a process of opening the valve,
Fuel cell system. The fuel cell system according to claim 1,
A supply channel for supplying anode gas to the fuel cell,
A circulation passage communicating the gas-liquid separator and the supply passage,
A pump that is disposed in the circulation flow path and supplies the anode off-gas after the water is separated by the gas-liquid separator to the supply flow path,
Further comprising
The stopping process includes driving the pump.
Fuel cell system. The fuel cell system according to claim 2,
When the stop processing including the driving of the pump is a first stop processing,
Even if it is determined that the valve is frozen, the control unit continuously receives a request to stop the fuel cell during the operation of the fuel cell and after a predetermined period elapses. If it is determined that the valve is frozen, a second stop process that is a second stop process different from the first stop process and that does not include the driving of the pump is performed.
Fuel cell system. The fuel cell system according to any one of claims 1 to 3,
A supply channel for supplying anode gas to the fuel cell,
A circulation passage communicating the gas-liquid separator and the supply passage,
A pressure sensor for detecting a gas pressure in the supply flow path,
Further comprising
The control unit determines the presence or absence of freezing of the valve by using a decrease amount of the gas pressure after transmitting the instruction with respect to the gas pressure before transmitting the instruction of the opening operation to the valve. ,
Fuel cell system. A method for controlling a fuel cell system, comprising:
The fuel cell system includes a fuel cell, a gas-liquid separator that separates water from anode off-gas discharged from the fuel cell, and a device that discharges the water separated by the gas-liquid separator from the gas-liquid separator. A drain channel, and a valve disposed in the drain channel to control discharge of the moisture from the gas-liquid separator,
When receiving a request to stop the fuel cell during operation of the fuel cell, a step of repeatedly determining whether the valve is frozen,
When the fuel cell stop request is received during the operation of the fuel cell, and when it is determined that the valve is frozen, the operation of the fuel cell is continued until it is determined that the valve is not frozen. The process of
Receiving a request to stop the fuel cell during operation of the fuel cell, and, when it is determined that the valve is not frozen, performing a stop process of the fuel cell including a process of opening the valve; and ,
Comprising,
A control method for a fuel cell system.

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